Now that the Bentley repair manual is out, it seems a bit pointless to write DIYs for repairs, since they are covered in the manual. But I have found that most repair manuals leave out the little details for the various procedures they cover, which are the things you really want to know anyway. With that in mind I decided to share a remove and replace DIY for one of the E90 N52 O2 sensors.

This DIY is for the Bank 2 Sensor 1 (the harder of the two up-stream sensors to replace). The good news here is once you get to it, it screws out of the manifold quite easily (good job BMW for using anti-seize at the factory and good exhaust manifold material - stainless steel), the bad news is getting to it.

This DIY is long, so I've made it as a MS Word file so it can be printed. As usual I didn't take any pictures (it takes too long to complete the job), but the DIY is descriptive enough that you really don't need any.

Thanks for sharing your experience. Not excited about removing all the cowling, cabin air filter, and other items just so I can remove engine cover .

So, when you removed the B1S1 sensor, did you have to remove anything that had to do with steering rack or tie rod? My Bentley manual said 'remove the right tie rod from the steering rack'

Also, was removal of the sensor fairly straightforward --- or did you really have to work at it or use the big breaker bar?

I bought an off-set type sensor socket --- is that what you use?

Thanks in advance EFT!

You must be talking about the B1 S2 O2 sensor then. The Bank 1 Sensor 1 is the O2 sensor in the top of the front exhaust manifold (cylinders 1, 2, 3) that you can easily see on the right side of the engine. This this for an N52 of course, which is the engine in your car. I have both types of sockets (off set and deepwell-split). Either should work.

I did my sensor just after the time Eninty posted the DIY and the price for the OEM sensor (B2 S1) was $55 from Tischer.

I'm certain about B1S1. I looked under the hood this AM. You are correct --- it is clearly visible and reachable w/o removing the engine plastic cover. However, to remove the O2 sensor wire plug/harness, it appears to be further towards the rear of the engine. I could not see where the wires ended. So, looks like I need to remove the engine cover.

Quote:

Originally Posted by Efthreeoh

You must be talking about the B1 S2 O2 sensor then. The Bank 1 Sensor 1 is the O2 sensor in the top of the front exhaust manifold (cylinders 1, 2, 3) that you can easily see on the right side of the engine. This this for an N52 of course, which is the engine in your car. I have both types of sockets (off set and deepwell-split). Either should work.

I did my sensor just after the time Eninty posted the DIY and the price for the OEM sensor (B2 S1) was $55 from Tischer.

I'm certain about B1S1. I looked under the hood this AM. You are correct --- it is clearly visible and reachable w/o removing the engine plastic cover. However, to remove the O2 sensor wire plug/harness, it appears to be further towards the rear of the engine. I could not see where the wires ended. So, looks like I need to remove the engine cover.

Has anyone got a diy with pics preferably for the N54, and are the 02 sensor specific wrenches/sockets worth purchasing or are these more of a 'nice' to have item?

There are pictures of how to remove the engine cover in other DIYs (for spark plugs and fuel injectors) but the procedure for the N54 is pretty much the same as for the N52. The O2 sensor harnesses for the two pre-cat sensors go underneath the engine cover and are routed in channels and harness clips that require removal of the engine cover. The post-cat sensors do not need the engine cover removed.

You can use a 7/8ths box wrench on the sensor if you can fit one on it, but you have to cut the cable off; the connector does not fit through the wrench opening. I don't think a 7/8 deep socket will fit over the O2 sensor even with the cable completely removed. The special sockets are not that expensive and every auto parts store will have the correct sized socket.